Even though insulating and heating technologies have become more sophisticated, the overall approach used by modern humans to defend body temperature against cold — insulating and heating themselves — is no different from the one used by the caveman. The study by Almeida et al. proposes a different approach: modulating deep body temperature by blocking temperature signals that drive thermoeffector responses by drugs.

In the study entitled "Pharmacological blockade of the cold receptor TRPM8 attenuates autonomic and behavioral cold defenses and decreases deep body temperature" (J Neurosci 32: 2086-2099, 2012), we used M8-B, a selective and potent antagonist of the transient receptor potential melastatin-8 (TRPM8) channel. M8-B decreased deep body temperature in Trpm8+/+ mice and rats, but not in Trpm8-/- mice, thus suggesting an on-target action. M8-B attenuated cold-induced c-Fos expression in the lateral parabrachial nucleus, thus indicating a site of action within the cutaneous cooling neural pathway to thermoeffectors, presumably on sensory neurons. At tail skin temperatures < 23°C, the magnitude of the M8-B-induced decrease in body temperature was inversely related to skin temperature, thus suggesting that M8-B blocks thermal (cold) activation of TRPM8. The TRPM8-antagonist-induced hypothermia is the first example of a change in the deep body temperature of an animal occurring due to demonstrated pharmacological blockade of temperature signals at the thermoreceptor level. A new discipline — thermopharmacology — has emerged. See comment on this study in the Scientific American.

Several recent papers from the leading laboratories published in the leading journals state that skin temperature is a feedforward signal for the thermoregulation system. In our latest review (Skin temperature: its role in thermoregulation. Acta Physiol 210, 498–507, 2014) we argue that this popular view is erroneous.

The body is covered mostly by hairy (non-glabrous) skin, which is typically insulated from the environment (with clothes in humans and with fur in non-human mammals). Thermal signals from hairy skin represent a temperature of the insulated superficial layer of the body and provide feedback to the thermoregulation system. This feedback is auxiliary, both negative and positive. It reduces the system’s response time and load error.

Non-hairy (glabrous) skin covers specialized heat-exchange organs (e.g., the hand), which are also used to explore the environment. In thermoregulation, these organs are primarily effectors. Their main thermosensory-related role is to assess local temperatures of objects explored; these local temperatures are feedforward signals for various behaviours. Non-hairy skin also contributes to the feedback for thermoregulation, but this contribution is limited.

Autonomic (physiological) thermoregulation does not use feedforward signals. Thermoregulatory behaviours use both feedback and feedforward signals.